The purpose of this research is to investigate the changes in the central nervous system control of gonadotropin secretion during sexual maturation of human beings. The proposed studies are based on the hypothesis that gonadotropin-releasing hormone (GnRH) pulse frequency plays a regulatory role in human sexual maturation and throughout the menstrual cycle. Specifically, we have proposed to evaluate the effects of the principal sex steroids, testosterone (T) and estradiol (E[2]), on GnRH secretion. We have also proposed to examine whether, and if so when, endogenous opioid pathways become involved in the regulation of GnRH secretion during human sexual maturation.